High-frequency electroexpansive tuning apparatus



Jan. 3, 1950 s.'F. VARIAN ET AL HIGH-FREQUENCY ELECTROEXPANSIVE TUNINGAPPARATUS Original Filed Aug. 3, 1942 INVENTORS AS. F. l/qR/Am BY 5.4G/NZTO/V m m? W ATTOR/VZY Patented Jan. 3, 1950 HIGH-FREQUENCYELECTROEXPANSIVE TUNING APPARATUS Sigurd F. Varian and Edward L.Ginzton, Garden City, N. Y., assignors to The Sperry Corporation, acorporation of Delaware Original application August 3, 1942, Serial No.453,482. Divided and this application July 13, 1944, Serial No. 544,730

20 Claims.

The present case is a, true division of our copending application SerialNo. 453,482, filed August 3, 1942, for High frequency tube structure,and now U. S. Patent No. 2,475,652, granted July 12, 1949.

This invention relates, generally, to ultra high frequency electron beamvelocity grouping tubes, and, more specifically, to improvements inoscillator or amplifier types of high frequency tubes of the generaltype disclosed in copending application Serial No. 420,771, entitledHigh frequency tube structures, filed November 28, 1941, in the names ofWilliam W. Hansen and John R. Woodyard, and now U. S. Patent No.2,450,893, granted October 12, 1948. in which velocity grouping tubesutilizing buncher and catcher resonators as well as a third resonatorserving as a buffer stage are described.

The purpose of the addition of this buffer resonator was to provide amore or less electromagnetically independent resonator from which largeand variable amounts of high frequency energy might be extracted withoutadversely reflecting back into the prior resonators and thereby alteringthe output frequency of the tube. In this type of tube this result hasbeen to a large extent accomplished since the only electromagneticcoupling between the buffer resonator and the earlier resonators isalong the interconnecting electron stream itself.

In this prior art disclosure, no means for gang tuning of the threeresonators was provided, a mechanical fine tuning device being generallyutilized to control the buncher or first resonator only, since thisresonator is the chief frequency determining element of the tube. Thisresonator and the catcher or second resonator as well as the bufier orthird resonator generally have coarse tuning means. Since the catcherand buffer resonators can be made to have broad resonance curves, suchcoarse tuning is usually suflicient, though the frequency range of thetube is naturally limited by the lack of fine tuning of the latterresonators.

One object of the present invention is to provide a simple gang tuningdevice for simultaneously changing the resonant frequency of as manyresonators of the high frequency type as may be desired.

A further object is to provide a gang tuning device in which equalparallel relative motions of the respective resonator grids or frequencycontrol elements of a multi-resonator tube may be produced.

A still further object is the provision of a gang tuning parallel motiondevice electrically controllable by a current which may be related tothe desired output frequency, and incorporating mechanical means forindependent coarse adjustment of individual resonators.

Other objects and advantages will become apparent from thespecification, taken in connection with the accompanying drawing whereinthe invention is embodied in concrete form.

In the drawing, the single figure is a fragmentary partial cross-sectionelevation View of a preferred form of the present invention.

Referring now to the figure, there is shown an electron beam velocitygrouping vacuum tube consisting of an indirectly heated oxide coatedcathode I placed axially in an end bell jar 2 in front of a smoothing oraccelerating grid 1, grid 1 forming an entrance into axially spacedresonators 3, 4 and 5. Resonators 3 and 4 are formed by a conductingtubular outer wall l2, flexible end diaphragms l0 and II, and flaredinner conducting tubes 8 and 9, which cooperate to form electron beamdrift space 6, and whose outwardly flared portions form a separatingwall between resonators 3 and 4. Holes 23 are placed in the flared drifttubes 8 and 9 in order to accommodate coupling loop :24, opposite endsof which ex-. tend into resonators 3 and 4. Grids l6, l6 and I8, I 8 areshown in resonators 3 and 4, respectively, through which the electronbeam from emitter I is projectedby a unidirectional acceleration voltageplaced between cathode l and grid 1. A tube l 9 projects from resonator4, on whichv tube is mounted a rigid end plate I'5 which, to-

gether with tubular outer wall I3, flexible end spaced circular coolingflanges H. An end cooling flange l'! is made of greater thickness thanfianges IT in order to prevent damage thereto due to handling. Similarcooling flanges BI and 5! are provided between resonators 4 and 5, andbetween resonator 3 and end bell jar 2, respectively.

Resonators 3, 4 and 5 are provided with similar concentric linestructures 25, 26 and 21 for the removal or introduction of energy fromor into any one or anycombination of these-respective resonators. Theseconcentric line devices consist of an inner conducting rod 29 terminatedinside of the resonator by a coupling loop 28, which joins directly tothe inner wall of a tubular outer conductor 30,. whose inner surface ispreferably plated with a highly conducting material such as copper orsilver. In construction, inner conductor 29, whose outer surface is alsopreferably plated with a highly conducting material is sealed by glassto metal end seal 33 concentrically in a short flanged tubular outerconductor 3|. The tube 30 is silver-soldered in position in theresonator wall I2 or l3, and the structure 29, 31, 33 is inserted intotube 30 and spot-welded at 32. The end of loop 28 and the inner wall oftube 33 adjacent thereto have been previously tinned with a soft solder,so that the application of a slight amount of heat to the exterior oftube 30 near its point of contact with loop 28 completes the electricaljunction. Thus, a method of assembly of the concentric line structure isprovided without exposing the glass to metal end seal 33 to the elevatedtemperatures necessary for silver-soldering tube 30 in place, therebyeliminating the danger of cracking seal 33 during attachment to aresonator. This method also eliminates oxidation of the inner surface oftubular conductors 30 and 3,! and the outer surface of conductor 29,thereby preventing the increased impedance which would naturally resultfrom such oxidation.

Flanges 48, 49, 50 and are provided on end bell jar 2, outer conductingwall I2 of resonators 3 and 4, outer conducting wall 13 of resonator 5,and finned end tube 20, respectively, in order to transmit relativemotion from the tuning device of this invention to the respective grids.Spaced directly oppositely on each of these four flanges at an angularseparation of substantially 120 are three holes through which areinserted three rigidly clamped exteriorly threaded thin tubes or thermalstruts 52, each of which extends parallel to the vacuum tube axis andprojects. slightly past flanges 48 and 5| at opposite ends. Each of; thethree thin tubes 52 is rigidly held at each flange in a thermallyinsulating clamp, each clamp consisting of an insulating bushing, 53,insulating washer 54, and on opposite. Sides of the flanges, two metalwashers 55 and two metal nuts 55. The ends of the thin tubes 52 areclosed by apertured insulating plugs 51, 51', through which heater wires58 extend. Heater wires 58 run the length of the tube 52 and may besupported therein by a powdered insulat g material such as magnesiumoxide, or may be supported only by the end plugs 51, 5 1. The ends, ofheater wires 58. in each of the three thin tubes 52 are, connected inseries by the leads shown and supplied with current controlled by arheostat. ill from battery 5.9. If desired, the inner and outer surfacesof tubes 52 may be treated in any well-known manner, as by coating thesame with a reflecting material, to increase or decrease thermalradiation from their surfaces.

In operation, the electron beam from cathode I is. acceleratedsuccessively through grid 7, grids I6, [6' of resonator 3, grids l1, llof resonator 4, grids 2t, 22, of resonator 5, and finally impinges uponthe inner wall of end tube, 25. Coupling loop. 24 m y be adjusted so.that the electrons arrive between grids l8 and I8 of resonator 4 in a,somewhat under-bunched condition, and do not obtain optimum bunchinguntil they arrive between grids 2| and 22 of resonator 5. Such anadjustment produces the result that resonator 4 is excited only so muchas, is necessary to properly excite resonator 3, while buffer resonator5, from which it is usually intended to. extract high frequency energy,is excited to the. highest amplitude o: oscillation, possible.

s is w ll nown. lectron beam velocity modulating tubes are generallyprovided with flexible diaphragms, such as diaphragms II, I 0, I4 ofresonators 3, 4, 5, respectively, in order to enable the changin of thedistance b tween the respective resonator grids and thus enableindividual or gang tuning of the resonance frequency of the resonators.Such tubes are also usually provided with flanges, such as flange 48 onend bell jar 2, flange 49 on resonators 3 and 4, flange 50 on resonator5, and flange 5| on finned end tube 20, which normally cooperate withmechanical devices for obtaining the desired relative grid motions. Inthe case of tworesonator tubes, gang tuning devices of mechanical typessuch, as those disclosed in prior application Serial No. 342,912,entitled High frequency tube structures and filed June 28, 1940, in thenames of William T. Cooke, Joe J. Caldwell, Jr., and David G. Clifford,have proved useful, but in the case of multi-resonator tubes, mechanicaltuning becomes a complex problem for the following reasons. Referring tothe drawing, if flange 5D. is relatively fixed and used to support thetube, as from an apparatus panel, it is seen that for gang tuning, ifflange 5! is moved one unit to the left, flange 49 must then be movedone unit to the right, and flange 48 must be moved two units to theright. A mechanical motion device to perform this function mustnecessarily be complex. Also, in gang tuning of multi-resonator tubes,which necessarily utilize long electron beams, there is the furtherrequirement that the flanges must all be moved absolutely parallel toeach other in order to preserve the alignment of the tube.

In the figure, it is seen that heat generated by current passing throughheater wires 58 will cause uniform thermal expansion of the thin tubes.52;, which in turn will produce equal parallel relative motion of theflanges 48, 48, 5B and 5!.. This motion of the flanges is transmitted tothe grids, changing the relative spacing thereof; resulting insimultaneous tuning of all resonators. A further advantage of this novelsystem of gang tuning is that it may readily be adapted to a system ofremote automatic frequency control by replacing battery 59 and rheostat60 by any suitab e voltage source which provides a current related tothe desired output frequency. Initial individual tuning of theresonators 3, 4 and 5. is accomplished by mechanical adjustment of the.nuts 56. This thermal type of tuning device may be equally well appliedto single-resonator, or to two-resonator tubes, or to tubes having aplurality of resonators, wherever tuning by parallel motion of theresonator grids is necessary, or wherever electrically controllableremote tuning is desired.

Since many changes could be made in the above construction and manyapparentl widely different embodiments of this invention could be madewithout departing from the scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

A high frequency tube structure comprising electronic means forproducing an electron stream, a plurality of hollow resonatorsconsecuti-vely disposed along the path of said stream, said resonatorshaving flexible wall portions to enable relative motion of opposite wallareas during the tuning of said resenators, and means for efi'ectinggang tuning of said resonators comprise ing a single thermal strutcoupled at different points along its length to each of said'flexiblewall portions of all said resonators, and heating means in saidstructure for heating said thermal strut along its entire length toeffect expansion and contraction thereof resulting in the deflecting ofthe flexible wall portions of said resonators and the gang tuning of thelatter.

,2. Apparatus as defined in claim 1, wherein at least one of saidresonators has an additional wall portion which remains fixed relativeto said flexible wall portion of said one of said resonators, said highfrequency tube structure further including an additional thermal strutcoupled to said additional wall portion and said flexible wall portionof said one of said resonators.

1 v3. A high frequency tube structure comprising electronic means forproducing an electron stream, a plurality of hollow resonatorsconsecutively mounted along the path of said stream, said resonatorshaving reentrant portions and flexible wall areas enabling relativemovement between said reentrant portions and the oppo-- site walls ofthe resonators for efiecting tuning thereof, said reentrant portions andthe said opposite walls of the resonators being apertured in said streampath, a plurality of thermally expansible and contractible elementsdisposed around and each connected to said reentrant portions and saidopposite walls of all said resonators, and remotely controlled means insaid structure for simultaneously heating said elements, wherebysimultaneous relative movementbetween said reentrant portions and theopposite walls of said resonators is effected while maintaining saidreentrant portions and walls substantially parallel, thereby eirectinggang tuning of said resonators.

4. High frequency tube structure comprising a substantially cylindricalmember, deformable walls at opposite ends of said member, alignedelectrodes in said deformable walls, wall means within said member rigidwith said member and substantially separating the space within saidmember into two resonator chambers, aligned electrodes in said wallmeans, each electrode on said wall means being located adjacent anelectrode in one of said deformable walls, a single longitudinallyexpansible and contractible thermal tuning strut connected at oppositeends to the electrodes in said deformable walls and connectedintermediate its ends with said electrodes on said wall means, and meanscoupled to said strut for electrically energizing said tuning strut,said strut being operable under varying degrees of energization tosimultaneously and similarly control the spacings between said adjacentelectrodes for gang tuning said resonators.

5. High frequency tube structure comprising electronic means forproducing an electron stream along an axis, a plurality of hollowresonators aligned parallel to said axis along the path of said stream,said resonator means having a plurality of pairs of relativelydisplaceable electrodes in said resonators, one pair being included ineach resonator, and a single thermal tuning element substantiallyparallel to said axis operatively connected to all of said electrodesfor simultaneously controlling the spacing between each pair ofelectrodes for gang tuning said resonator means.

6. The high frequency tube structure defined in claim 5, wherein saidelectrodes of each pair; are substantially parallel, and a. furtherthermal tuning element operatively connected to said pair ofelectrodesat at least two points along said further tuning element for controllingthe spacing between the electrodes to effect substantially parallelrelative movement of said electrodes.

7. High frequency tube structure comprising electronic means forproducing an electron stream, hollow resonator means alongthe path ofsaid stream, said resonator means having a plurality of pairs ofrelatively displaceable electrodes inadjacent walls of said resonatormeans, means rigidly interconnecting one electrode of one of said pairswith one electrode of another of said pairs, and a single thermal tuningelement operatively connected to all of said elec-- trodes forsimultaneously controlling the spacing between the electrodes of each ofsaid pairs for gang tuning said resonator means, said ther mal tuningelement comprising an electrically.

energizable element connected at one end to the other electrode of oneof said pairs and at the opposite end to the other electrode of anotheroi.-

said pairs, and connected intermediate its ends to said rigidinterconnecting means.

8. A high frequency electronic tube comprising a hollow structure,deformable walls at opposite ends of said structure, aligned electrodesshiftably mounted in said walls, wall means within said member forseparating the space within said structure into two adjacent resonatorchambers,

aligned electrodes on said wall means, said elec-' trodes on said wallmeans being fixedly spaced and each being located closely adjacentanother electrode on one of said deformable walls, and

an expansible and contractible thermal tuning. member mounted on saidhollow structure with its opposite ends connected to said shiftablymounted electrodes, and connected intermediate its ends to theelectrodes on said wall means, said tuning member being electricallyenergizable to similarly control the spacing between the electrodes ofeach said pair.

9. High frequency apparatus comprising means for producing an electronstream, hollow resonafor means algined along an axis and adapted tocontain oscillating electromagnetic fields and arranged along the pathof said stream for interaction therewith, individual members on saidresonator means shiftable for tuning each of said fields, and a singlethermally controlled element substantially parallel to said axisconnected to all said members for simultaneously and similarly varyingthe resonant frequency of said fields.

19. A high frequency tube structure comprising electrode means forproducing an electron stream, three hollow resonators consecutivelydisposed, along the path of said stream, four individual tuningadjusting means coupled to said resonators, and a single thermallyenergizable tuning element connected to all said individual means, saidtuning element being connected to each of said individual means at adifferent point along its length for simultaneously adjusting thefrequency of said resonators.

11. Ultra high frequency tube structure comprising electronic means forproducing an electors, said elements being oppositely movable for,effecting similar changes of frequency therein,

15' anda single linear thermally expansible member.

amen

attached. at an intermediate point to said base and at opposite endstosaid tuning elements for simultaneously and: similarlyvarying the.rear-- nant frequencies. of said resonators.

12. Ultra high frequency apparatus comprising means defining apair ofaligned resonator chamhers, means at each resonator for individuallytuning: each of said resonators, a single thermally expansible andcontractible' element connected to all. said individual tuning means forsimultaneously tuning said resonators, and: means in said apparatus forcontrolling thermal energization of said expansible and contractibleelement, sai'd single element being connected, to said tuning means atat least three points along said single element;

. 13'. Ultra high frequency apparatus-comprising electronic means forproducing an electron stream, means defining a pair of resonatorchamhers disposed along the path of said stream, shiftable electrodemeans in. each of said resona-- tors; individual tuning adjustment meansconnected to each shiftable electrode means, and a singlethermallyenergized tuning. element connected to all said individualmeans at at least three. points along said; tuning element forsimultaneously adjusting the frequency of saidresonator chambers.

:14. The ultra high frequency apparatus defined in claim 13; whereinsaid resonator chambers'are provided. with deformable walls, and saidshiftable electrodes are carried by said walls.

15. High frequency apparatus comprising a plurality of consecutivelyaligned cavity resonatorseach having a pair of relativelymovable ele-IHBHtS; for efi'ectingl tuning thereof, means con-- necting one elementof each resonator to an element of a succeeding resonator, athermallyexpansible. strut rigidly connected at different points along its lengthto one element of each resonator, and heater means adjacent said strut.

for applying heat thereto to produce thermal ex-- pansion of said strutand consequent gang tuning of said resonators.

16. High frequency apparatus comprising a pair of consecutively alignedcavity resonators each having a pair of relatively movable elements. foreffecting tuning thereof, means connecting, one element of one of saidresonators to an element of the other of. said resonators; a thermallyex-pansible strut rigidly connected at one point to the other element ofthe first of said resonators, at a second point spaced therefrom to theother element of the other of said resonators, and at an intermediatepoint to. said interconnected cments; and heater means adjacent saidstrut for. applying heat thereto to produce thermal ex,- pansion of saidstrut and consequent gang tuning of said resonators.

17. High frequency apparatus comprising a pair of consecutively alignedcavity resonators each having a pair of relatively movable elements forefiecting tuning thereof, means rigidly connecting one element of one ofsaid resonators to an element of the other of said resonators, and anelectrically controllable thermally expansiblestrut rigidly connected atone point to the other element of said one resonator, at a separatedpoint to the other elementof said other resonator, and at anintermediate point to said connected elements, whereby, uponenergization of said strut, expansion thereof is produced for gangtuning said resonators.

:18; High frequency apparatus. comprisinga.

pair ot cavity resonators each having; a pair of 8 parallefelementserelatively movable along a com-' mon axis. for effecting tuning of saidresonators, means rigidly connecting one element 01 one of saidresonators to an: element of the other of said; resonators, and aplurality of similar electrically energizable thermally expansiblestruts symmetrically disposed about said: axis and each rigidlyconnected at one point to the other element of said one resonator, at aseparated point to: the other element of said resonator, and at anintermediate point to said connected elements; said plurality of strutsbeing simultaneously controllabl'e' in equal extents whereby, upon.electrical energization of said struts producing expansion thereof, saidpairs of elements are relatively moved to produce gang tuning of saidresonators with said pairs of elements being retained mutually parallel.

19. High frequency apparatus comprising three consecutively alignedcavity resonatorseach having a pair of relatively movable elements foreffecting tuning thereof, means connecting oneelement of a firstresonator to an element of a; second? resonator, means connecting theother element of said second resonator to an elementof said: thirdresonator, and an electrically ener gizable expansible strut rigidlyconnected at one point to the other element of said first resonator, ata separated point to the other element ofsaitl third resonator, and at apair of separated points intermediate said first-named points,respectively to first andsecond connecting means, whereby; uponelectrical energization of said strut producing expansion thereof, gangtuning of said three resonators is effected.

20; High frequency apparatus comprising aplurality of tuned circuitseach having apair of relatively movable elements for effecting tuningthereof, said pairs of relatively movable elements being connected toaligned electron-permeable regions, means connecting one element of. oneof said circuits to. an element of a succeeding circuit, andelectrically energizable expansibl'e strut means rigidly connected atone point to the other element of said first resonator, at a separatedpoint to the element of said succeeding circuit, and at an intermediatepoint to said connected. elements, whereby, upon electrical energizationof said strut to produce expansion. thereof, gang tuningv of saidcircuits is efiected.

SIGURD F. VARIAN. EDWARD L. GINZTON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date" 1,559,714 Lilienfeld Nov. 3,1925' 1,658,953 Theremin Feb. 14, 1928- 2,162,343 Brace June 13, 19-392,216,170 George Oct. 1, 1940- '2,222,902 Hahn Nov. 26, 1940 2,311,658Hansen et a1 Feb. 23, 1943 2,345,642 Varian et al Apr. 4, 1944 2,408,817Snow Oct. 8, 1946 2,414,785 Harrison et al Jan. 21, 1947' FOREIGNPATENTS Number Country Date 53.7.,518- Great Britain June 25, I941

